White 92mm FPL-53 ED Refractor Telescope TMB Optical
This 92mm refractor telescope from TMB Optical is extremely compact, which gives it a good rank for portability when observing. This tiny optical tube has high quality optics and is great for both visual observing and solar and deep sky astrophotography. Since this telescope has ED glass, aberration is no longer an issue. This results in pinpoint stars which is great for getting high contrast images. TMB Optical has added excellent anti-reflection coatings that help make this scope so detail oriented!
Apochromatic triplet ED refractor optics - 3.6” (92mm) aperture, 506mm focal length, f/5.5 triplet lens. It uses an FPL-53 ED (Extra-low Dispersion) glass element for a sharp and flat field and images that are high in contrast and free from spurious color (chromatic aberration).
Multicoated optics - Fully multicoated on all surfaces with the latest antireflection materials for exceptionally high light transmission and excellent contrast. Light transmission is so high that the optics seem to virtually disappear when viewed from head on.
Collimatable lens cell - The lens cell has three sets of push/pull collimating screws that will let you tweak the optical collimation after rough handling or extensive travel. This assures that optimum visual and photographic performance is only a few moments away.
Internal light baffles - Contrast-enhancing knife-edge light baffles in the optical tube and focuser provide truly dark sky backgrounds and high terrestrial contrast. In addition, the edges of the objective lens are blackened to eliminate contrast-reducing stray internal reflections.
Retractable dew shield - The self-storing retractable dew shield/lens shade slows the formation of dew on the lens to extend your undisturbed observing time. It also improves visual and photographic contrast by shielding the lens from off-axis ambient light (the neighbor’s yard light, moonlight, etc.)
Dual-speed microfine #3025 3” Feather Touch rack and pinion focuser - The precision-made 3” diameter drawtube non-vignetting focuser is a genuine Feather Touch from Starlight Instruments, a company known world-wide for making the finest and most reliable focusers available to the amateur astronomer. The focuser has dual-speed focusing. There are two coarse focusing knobs. The right knob also has a smaller concentric knob with a 10:1 reduction gear microfine focusing ratio. This provides exceptionally precise image control during very high magnification visual observing, and during critical 35mm or CCD imaging. All focus knobs are ribbed, so they are easy to operate, even while wearing gloves or mittens in cold weather. Multiple internal baffles in the focuser drawtube assure high contrast.
Rotating eyepiece holder - The entire focuser can be rotated a full 360° without disturbing the focuser drawtube position. This lets you rotate the eyepiece/accessory holder to line up a camera in either a landscape or portrait orientation (or any orientation in between) without disturbing the focus, as well as put a star diagonal and eyepiece into the most comfortable observing position. Three large locking knobs on the focuser body let you temporarily lock your camera or accessories in the desired orientation, then change that orientation with a simple twist of the wrist.
Focusing scale - The 65mm (2.65”) travel focuser drawtube has a scale marked in 1mm increments so you can note individual focuser positions for easy return to the correct focus when switching between visual use and photography. A large lock knob on top of the focuser lets you lock in your photographic focus.
Extension tube - The minimum length of the TMB-92 is 13.25” with the dew shield and focuser retracted for traveling and for long equipment train CCD imaging. A 2.25” extension tube is supplied to provide the proper back focus for convenient visual use and 35mm/webcam/Deep Sky Imager type astrophotography. This installs between the optical tube and focuser. A groove in the extension tube engages the brass thumbscrews in the optical tube (that normally control focuser rotation) to hold the extension tube firmly to the optical tube. Three nylon-tipped metal thumbscrews at the opposite end of the extension tube now hold the focuser in place and allow focuser rotation, just as the brass thumbscrews in the optical tube do when the extension tube is not used. A Teflon insert in the focuser end of the extension tube assures smooth focuser rotation. When the extension tube is not used, the available back focus allows you to reach focus with virtually any combination of photographic accessories (CCD camera, filter wheel, electric focuser, adaptive optics system, etc.). When the supplied 4” diameter by 2.25” long extension tube is threaded into place between the focuser and the optical tube, the maximum overall scope length is increased to 20.75”, the proper length to achieve visual focus with a star diagonal and eyepiece.
Compression ring eyepiece holders - The focuser drawtube ends in a 2” eyepiece holder that uses a non-marring soft brass compression ring to hold a 2” star diagonal and accessories in place. The compression ring won’t scratch the barrel of your star diagonal and accessories as an ordinary thumbscrew can. Also supplied is a 1.25” eyepiece holder that slips into the 2” compression ring holder to let you use a 1.25” star diagonal or image erecting diagonal. Like the 2” eyepiece holder on the eyepiece holder rotation mechanism, the 1.25” adapter also uses a non-marring soft brass compression ring to hold 1.25” star diagonals and accessories in place. The 2” accessory holder can be removed from the drawtube to allow the installation of custom A-P type photo accessories available directly from Starlight Instruments.
Finderscope mounting point - No finderscope is provided with the TMB-92, but two finderscope mounting points are located at the 2 o’clock position on the Feather Touch focuser body. Only one of the mounting points is needed to install an optional Astro-Tech #ATF multiple reticle finder. The finder’s mounting stalk can be attached to the scope using either of the screws normally threaded into the mounting points to prevent the entrance of dust. If you prefer to use an existing 50mm finder, you can mount it on either of the scope’s mounting points by means of an optional Astro-Tech #ATFB mounting base and optional Losmandy #LQRB quick-release finder bracket, as shown in the feature image below.
Tube finish - The 114mm o.d. optical tube is finished in a durable baked-on automotive white paint with a black-anodized focuser, trim, and 2.25” extension tube.
Shipping/storage case - The TMB-92 comes standard in an aluminum frame 22.25” x 12.75” x 8” locking hard case with a carry handle for transportation and general protection purposes. TMB Optical is one of the very few manufacturers to provide a case at no charge for protection during shipping and as a storage convenience when the scope is not in use. Unfortunately, FedEx, UPS, and the Postal Service are very good at treating packages roughly. Occasionally, your scope can arrive in perfect condition, but with the walls of the shipping case dented in transit from rough handling, or the aluminum frame sprung, rendering the appearance of the case less than pristine. Damage to the shipping case in such instances is not covered by warranty.
Other supplied accessories - A slip-on metal dust cap is standard. As mentioned previously, threaded holes for installing a finderscope bracket are located on the upper right side of the focuser body.
Two year warranty - As an expression of the confidence TMB Optical has in the quality of their products, the TMB-92 is protected by a two-year limited warranty against flaws in materials and workmanship (shipping case excluded).
|Highest Useful Magnification||204x|
|Limiting Stellar Magnitude||12.3|